为什么使用活动上下文会导致上下文内存泄漏

Question

I've searched many times on Google about "use Application Context or Activity Context ".

Most of the answers are: "Use application context getApplicationContext() as much as possible to prevent Context memory leak".

I am confused:

Why using Activity context may cause memory leak although:

" Activity context is associated with to the activity and can be destroyed if the activity is destroyed"

BUT

" Application context is associated with the application and will always be same throughout the life of application -- it does not change" ?

Answer 1

Activity instances are transient: they come and go based on user interaction with your app. Your app overall has a single Application instance which exists for the lifetime of the process of your app. Take a simple example: the user starts your app via the launcher (home screen), your MainActivity is created and launched. If this was the first launch then your app's process is started an an Application context created as well. The user presses the BACK key and your MainActivity is exited, going through its onDestroy() . Now if the user re-launches your app, a new instance of MainActivity is created. However, your app's process was not killed (assuming there was no memory pressure) so the Application object singleton still exists and is valid. Your original MainActivity instance does not exist.